<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        canvas {
            border: 1px solid red;
        }
    </style>
</head>
<body>
    <canvas width="500" height="500" id="mycanvas"></canvas>
    <script>
        let canvas = document.querySelector("#mycanvas");
        // 获取上下文 ；画笔
        let context = canvas.getContext("2d");

        function loadImg(){
            return new Promise((resolve,reject)=>{
                // let img = new Image()
                let img = document.createElement('img')
                img.src = "https://gimg2.baidu.com/image_search/src=http%3A%2F%2Fimg.jj20.com%2Fup%2Fallimg%2Ftp09%2F210F2130512J47-0-lp.jpg&refer=http%3A%2F%2Fimg.jj20.com&app=2002&size=f9999,10000&q=a80&n=0&g=0n&fmt=auto?sec=1661398860&t=33a33d1ebc8ae7b6221a2985f122c83f"
                img.onload = function(){
                    resolve(this)
                }
                // 图片加载失败
                img.onerror = function(){
                    reject('图片加载失败')
                }
            })
        }

        loadImg().then(img=>{
            context.drawImage(img, 300, 300, 300, 300);
        },Error=>{
            console.log("error",err);
        })
    </script>
</body>
</html>